Creative Design
My job as a lecturer in the Multimedia University Malaysia covers a wide scope. It is not limited to only art. We are very much into photoshop and one of the thing that we do with photoshop is almost similar to doing caricature.
First we find a reference. It is important to find the characteristic of the subject being referenced. In this particular subject we identify a few of his personal traits and features and then our next step is to enhance these features.
Next we separate out the ears, eyes, nose and mouth.
I think this subject has his features that identifies him is his mouth. A wide smile that shows the teeth. Play on that feature. Usually we enhance it. The subject also has quite prominent cheekbones.
He has a noticeable nose. Once these features are identified, the next is we place on the proportion. The body will be manipulated to give it a cartoonish feel, just like in a caricature.
Practice Identifying Features
You can do a simple exercise by identifying some personalities. Such as Donald Trump and Bill Gates.

credit to @zomagic